With its limited land mass, real estate in Japan is a premium commodity. As such, there isn't a lot of extra urban space for private gardens—unless you build it on your roof, that is.

Dubbed the Optical Glass House, this 330 square-meter building was designed by famed Japanese architect, Hiroshi Nakamura, and resides on a busy street in downtown Hiroshima. Its glass facade is comprised of 6,000 clear, soundproof acrylic blocks, connected like a string of pearls by steel wire. This allows for light and air to penetrate the wall but dulls the din of vehicles and gives pedestrians a view of the interior garden.